The present invention relates to a signal demodulation apparatus and related method, and more particularly to an analog NFC signal demodulator and related method.
Short-range, standards-based contactless connectivity technology such as Near field communication (NFC) uses magnetic field induction to enable communication between electronic devices in close proximity. Based on RFID technology, NFC provides a medium for the identification protocols that validates secure data transfer. The signal of the NFC is modulated by ASK (Amplitude shift keying) modulation. To receive the data of the NFC signal correctly, the envelope of the NFC signal should first be extracted. In other words, the rising edge and the falling edge of the envelope of the NFC signal should be precisely detected in order to correctly demodulate the data of the NFC signal. Conventionally, a digital demodulation scheme is always used to demodulate the NFC signal because the digital demodulation scheme can easily handle various modulation schemes of the NFC signal. However, the digital demodulation scheme is expensive in terms of die. This is because at least one high resolution analog-to-digital converter must be used to convert the receiving signal into the digital signal, and the analog-to-digital converter always occupies a large area of the die. Moreover, the large power consumption of the analog-to-digital converter can be another drawback of prior art. Therefore, providing a simplified, low cost, and low power demodulation scheme to detect the envelope of the NFC signal is an urgent problem in the NFC field.